1. Field of the Invention
This invention generally relates to an AV device.
2. Background Information
The HDMI™ (high definition multimedia interface) standard is widely used today as a digital interface for connecting two or more electronic devices. Video signals, audio signals, and various kinds of control signals are sent in HDMI standard, by the TMDS (transition minimized differential signaling) method, from a source device to a sink device. TMDS allows the video signals, the audio signals, and various kinds of the control signals to be sent and received with a single cable.
However, when a television set or other such sink device is connected by HDMI to a DVD player or other such source device, a screen saver or other such video signal is outputted from the source device to the sink device. A screen saver is not something that the user generally watches by choice. However, since a television set receives the video signals, it will display this video (i.e., the screen saver). Thus, the duty ratio of a backlight of the sink device is kept high (i.e., at the same level as during normal video display), and this wastes power.
In view of this, a conventional display device determines whether or not an inputted video signal is a screen saver based on the ratio of the signal level that is lower than a reference signal level out of the video signal in a specific partial region (see Japanese Unexamined Patent Application Publication No. 2002-351420 (Patent Literature 1), for example). If it is a screen saver, then a brightness adjustment signal is sent such that the brightness will be adjusted to the level used for the screen saver, and the brightness of the backlight is lowered based on this signal.